题目内容
如图所示的电路中,电路消耗的总功率为40W,电阻R1为4W;R2为6W,电源的内阻r为0.6W,电源的效率为94%,求:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241542091272714.jpg)
(1)a、b两点间的电压
(2)电源的电动势
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241542091272714.jpg)
(1)a、b两点间的电压
|
(1)4.8V (2)20V
试题分析:(1)由题知电源的效率为94%,则电源内部消耗的功率为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154209517672.png)
又
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154209627516.png)
联立解得I=2A
则ab两点间的电压为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154209720873.png)
解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154210001673.png)
(2)由电源的总功率等于电路消耗的总功率
则有
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154210141540.png)
解得E=20V
点评:关键是分析电路中功率的分配关系,注意功率与效率不同,不要混淆;掌握电源的总功率
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824154210329453.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目